As disclosed in DE Patent application publication No. 102011056225A1 (which will be hereinafter referred to as Patent reference 1), generally, a known door check apparatus is provided between a vehicle main body and a vehicle door, and generates a resistance force (which will be hereinafter referred to as a holding force) against an opening and closing operation of the vehicle door. The holding force acts, at a hinge portion between the vehicle door and the vehicle main body, to hold a distance between the vehicle door and the vehicle main body.
When an opening-and-closing-operation force which is greater than the holding force is inputted to the vehicle door, the vehicle door opens and closes. The door check apparatus can restrict the vehicle door from performing the opening and closing operation against an intention of a user, for example, in a case where the vehicle door is kept open at a predetermined opening degree on a hill road and the vehicle door happens to close, or in a case where the vehicle opens widely further from a desired opening degree when the vehicle door is fanned by a wind or the like.
A door check apparatus disclosed in Patent reference 1 generates the above-described holding force with the use of a nut and a spindle (threaded rod). Specifically, the nut is arranged to be rotatable at a predetermined position at an inside of a vehicle door, and the spindle is connected to a vehicle main body side. The spindle moves in an axial direction in response to an opening and closing operation of the vehicle door. The nut and the spindle are threadedly engaged with each other, and a linear motion of the spindle is converted into a rotational motion of the nut. By controlling the rotations of the nut with a brake mechanism, the linear motion of the spindle (the movement of the spindle) can be stopped at an arbitrary position. Thus, the door check apparatus can generate the holding force at a position with an arbitrary opening degree (for example, a position at which a user stopped the opening and closing operation of the vehicle door).
According to the door check apparatus disclosed in Patent reference 1, in response to the opening and closing operation of the vehicle door, the spindle that is in the non-rotating state moves in the axial direction relative to the nut rotating at the predetermined position. It is configured such that the spindle itself is exposed outside at the hinge portion between the vehicle door and the vehicle main body in a state where the vehicle door is open. Thus, in a case where any specific measure has not been taken, rainwater and/or dust is likely to attach to an outer circumferential surface of the spindle. The adhesion of the rainwater and/or dust might lead to malfunction and/or occurrence of abnormal noises, and/or might shorten a service life of the door check apparatus.
A need thus exists for a door check apparatus which is not susceptible to the drawback mentioned above.